Centrifugal mold and core



R. J. MILLER 2,663,059

CENTRIFUGAL MOLD AND CORE Dec. 22, 1953 3 Sheets-Sheet 1 Original Filed July 20, 1945 INVENTOR. FaVqMG/ J Dec. 22, 1953 R. J. MILLER 2,663,059

CENTRIFUGAL MOLD AND CORE Original Filed July 20, 1945 I5 Sheets-Sheet 2 INVENTOR. Fat y/W017i] T/V z'ZZe/r Dec. 22, 1953 R. .1. MILLER I 2,663,059

CENTRIFUGAL MOLD AND CORE Original Filed July 20, 1945 5 Sheets-Sheet 5 [N V EN TOR. E 2 Fafi/r/O/IJ IMZZ/f' Patented Dec. 22, 1953 ween-C G 'IRIFUG U D DCW Rams. Miller, Detroit, Mich. 'origifialfanpllcati'on july 2o';---1945,' ser l a. '606,089. "Divided and thisapplication July 6, i M 52$P lN 7 32 v z'olai s. c1. 22f ]1"1s.5i-"f This invention relates to the art ofcasting, and

more particularly to the control of the temperatureof a mold before, during and after the'filling ofthe casting cavity to insure' complete fillingof the mold, and to, induce. progressive isolidificae the formation of shrinkage strains. :.5.-

tion of the casting toward] the feeder. to prevent,

This-application is a division of my copending:

application Serial No; 606,089, filedJuly 20, 1945,

forTemperature Control .Mold; 110W Patent 2,536,692; issued January 2,1951. 1, r

Difficulties "have heretofore beenlencountered in the casting of articles having thin sections because of thechilling effect of the; mold on the molten material cast into a zmoldecausingdt to solidify'before the castingcavitylwas completely filled; Partially .formed castings, or ,wcastings having high shrinkage strains :res'ultedm In an;

effort 't'ofinduce complete fillingofithewmold it hasbeen customary to heatxthej molten-alloy or metal considerably above its normal casting temp-l perature to overcome the chilling :efiect, caused by contact with the surface of. the mold. Difii-- culties have been encountered wherethis practice;.

hasbeen resorted to:.because in the casting of;

certain'materials under superheat conditions the physical properties of1the material are destroyed,-

whereupon castings having low physical properties result. I have found that these. difficulties;

can be overcome and castings'havingvery thin sections can advantageously be cast if the moldis heated to such an extent as to prevent a chilling of the molten material until the casting cavity is completely filled.

Inthe casting of certain materials, example as aluminum, -it-is-desirablethat the such for V castingbe cooled rapidly to effect quick solidification of the molten .alloy or metal to provide a smooth textured surface and fine grained metal structure. It has been impossible heretofore to efiec't rapid solidification'of castings having thin U sections because of the impossibility of completely filling the casting cavity before the molten'material chills to such a point that the cast ma--- terial will not flow readily to insure complete filling of the casting cavity.

An object of this .invention is therefore to provide means for: controlling the temperature 'of molds'to insure complete filling of casting,

cavities having thin walled sectionsbymaintaining the mold, in a heated conditioni'until' the,

molten material has completelyjfilled the casting cavity. v A further object and cooling a mold to permit complete filling of the casting cavity andtoinsure-rapid solidifica tion of the: casting-to :provide: a solid casting of; fine grained metal'structure having high-physical propertiesand 'a smooth textured surface. 5-

Another object is to-fiowa heat transferme dium over thewalls of a mold to impart-.progres sively decreasingheat to the-mold as the feeder passage is approachedto-maintain molten ma-e terial cast into the-moldin theliquid state'until the 1 casting cavity -is;completely filled.-- Yet a further "object; 0f"the invention residesin the provision of fluid passagesadjacent a mold to permit successive heating and cooling of the; mold from points'remotefrom the feeder toward the feeder to insure complete filling-ofcast-ing cavities having thin walled sections, and to permit rapid solidification" ofthe cast substance toward. the feeder passage tominimize shrinkage strains and. provide solid castings having 'smoothtextured surfaces.

Still another object of, the inventionis to pro; videa rotatable casting-machine having a cen--- trally disposed feederand'.aradially extended casting cavity wherein. meansware providednto n successively flow heat transfer mediums .over. the mold adjacent the. oute edges of the castingcavity toward the feeder to first heat the. mold to insurecomplete filling of the castinglcavity, and thereafter to -chill the mold to effect -rapid; solidification of the casting. c,

Another object resides inthe formation of V molds adapted to receivespacedcores toprovide a castingcavity having thin walled sections, and wherein controlled .heat transfer means are veme ployed to heatthe mold to insure complete filling. of the casting cavity, and to chill the mold to effect rapid and progressive solidification of the casting toward. thefeeder passage- Other objects and advantages ,of. this invention will be. apparent from the following detailed de scription considered inppnnection with, theace. companying drawings, submitted for purposesof illustration only andnot intendedto define the scope of the invention, reference being, .hadpfor that purpose .to the subjoined claims.

In. the drawings; wherein similar preference. characters refer to similar parts throughout the, several views: 1 f

Fig. 1 is a plan/view, partly broken away, .of I a casting venti'on.,j..

Fighz'isa sectional view taken substantially. flih l -e of-{Eia l looking-in the-directioni,

oftlie arrowsfi mfi nl odying the. present in}. I

Fig. 3 is a fragmentary sectional view taken substantially on the line 33 of Fig. 1, looking in the direction of the arrows.

Fig. 4 is a fragmentary sectional view taken substantially on the line 44 of Fig. 1, looking in the direction of the arrows.

Fig. 5 is a view similar to Fig. 1 showing a modified form of the invention.

Fig. 6 is a sectional view taken substantially on the line 66 of Fig. 5, looking in the direction of the arrows.

Fig. '7 is a longitudinal sectional viewer acasting machine embodying a still further modified form of the invention.

Before explaining in detail .therpresentginvena 'by' means of their associated locating pins 33 and 46 -projecting-into apertures in the bottom mold lining member 22.

' -A=spacing tube 48 is provided with a flange 50 tion it is to be understood that-the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carriedout inwariousrways." Alsoit is to beunderstoodstheiphraseologyeor 3;:

terminology employed herein? is- .for the purpose of description and not of "limitation.

Referring to Figs; 1 to riewiu benotedthat a bottom heat transfer jacket [0 is securedfto-a rotatable base l2,-andis provided with an up wardly extending flange 4 'at its per-ipheryiv The flange l4 supports a downwardly-extending flange i6 carried by an upper heat"transfei jacket 48 secured to the bottom heat-"transfer jacket l o as by studs Bottom and top mold lining members 22 and'24 are-interposedbetween the; bottom and top heat transfer-jackets "l0"aiid l8 respectively, and haveradially-extended portions 26 and 28 adapted to be engag'ed by the bottom and top heat transfer'jacket's" l'll and"=l8 inside of the flanges l4 and [6 respectively. A plurality of removable-"core memb'ers BO and 32 may Ice-interposed bet-ween the bottom an'dtop mold lining members 22 and 24 tocontour the space between the mold-liningmem'bers-M and-24 in any desired configuration-such-for= example as to form an impeller having passageways to direct the flow of air-or otherfiuid.

The cores 30and 32 are-formed of'amoldable substance. Where the'articl'e'being cast-is formed of an alloy such as aluminum; "brass 'or any" substance having apouring temperature of less than approximately 2,000 Fgthe cores may be" formed of plaster or the equivalent. 'f'In instances where the article being cast is formed o'f'a substance having a pouringtemperaturedn excess of 'f approximately 2,000 F.,:such. as .steel and the higher melting alloys, the'.cor'es30"';and 32Jare formed. of si1ica,.crystabolite,or other such suit-.

able substance. 7

The outer ends of the-cores 230andi'i32are bonded to fixtures having .spacednapertiures to receive pins carried by a .core .locatingri'rig 34 positioned on theflat'outer portionl26"of the bottom mold lining membe'r22 betweenthelflange l4 and an upwardly extending'jlan'ge 36 iormed on the bottom mold .lining member .22.. The core locating ring 34 is positioned in a predetermined location relative to the bottom 'r'rioldlining member 22 by means of a pin 38..carriedvby'the.lining 1 member 22 to project'into an aperture-Iinthe mold locating ring 34.

The inner ends of the ;cores vv3ll"and ,32- are bonded to core locators"40 having rectangular body portions and pins 42 projecting intothe' core forming substance. 'Atbottom 'coregjindex plate 44 having radiallyextended slots is pro-' vided to receive the rectangular body'portionsof Qto engage thelinnervends or toes 52 of the cores 30-to.:-ho1d the -inner ends of the cores in place. Theaspacingntubeyi48ris provided with a downwardly extending projection 54 to project into an aperture in the core index plate 44 to locate the tube 48 in a predetermined position relative to I the .lowericorezindex plate .44 :and corerlocating-ring34.

An upper core index:plate Behaving radially extending grooves is providedsto receive the rectangular body 'portions'tof "the-upper core locators 40 having ipinsfi42rbondedrin"the bodies 'of the cores 32. The.spacingr-.tube-'48-is provided with an axially extending'.slottto receive an inwardly extending projection SBcarriedby'the upper core 1 index plate '56 to:-1accuratelytlocate. theupper core index plate .56' i'vith reference to the lower core indexfiplate fl' andz'the outer core locating ring- 34;

It will be noted thatxhe" inner. and outer ends of the lower "and upper cores 30 and 32 are thus accurately located irelative to each other to in sure uniform spacingiof theeores. Core members of suitable "configuration'c'can zbe:formed and accurately located at spacedzpoints" in mold lining members "of suitable contour to insure the formation I of articles 0f virtually any complexity including very thinwall'ed sections; All of the cores of" any necessary contours to shape the desired castingcavitymay' be formed in a single core box to insure identity ofcontourof the core members.

A'pressure-ring' -W- is positioned on the'core locating-ring 34 to engage the outer endsee of the cores i3fl ito hold them in place. The top mold lining member 24 'h'asa locatingflange fill-to accurately locatet-he inner edge oi the core pressure ring 58.

A heat '-tr'arisfer separator "62 is secured to the bottomheat-transfer jackt ll] and is separated therefrom by means of spacers 64 'to diVide the space between thednner'surfaceof the-heat transferjacket HFand-theouter "surface of the mold lining 22'. 'Inlet passages '54 forheat transfer mediums are formed in ahousing GEsecured-in the rotatable base ,l2land'communicate with a space 68 between the heattran'sfer separator 62 and the bottom heattransfer jacket l0. 1' A portion of the heat transfer. mediums. flow around the ends of theseparatorw62-intoa space .13 between the separatorfibandzthe outer surface 'of the mold lining member 22. The heat transfer mediums flow radially: inwardly rzalongxthe outer surface ofct'he' moldliningmemb'er:22; and escape through outlet"'openingsi12 and passage 1-14 leading to waste. -As illustrated'in Fig.3; a metered portion of the heat transfer mediums-flow through aligned passages 16;[8and' 'formed in the'outer edges of the bottom and. top coolant jackets It and I8 into a-cOolantspace 82 tormed between the inher suriaceof the-"upper heat 'transfer' jacket I 8 andthe outer surface of the upper mold lining wardly alon'gthe outer surface of the upper mold lining member 24 from the passages 80 through.

c heat transfer mediums flow radially in-ff aee'agoi'so 1 the space 82 to outlet passages 84 in fittings 86 inter-connected by conduits 88, passageways 90',

conduits 92 and fittings 94 withp'assages'QG communic'ating withthe passage leading to waste-..

It will be noted that the outlet passages extend.

through-the outer flanges of the heat transfer housings l0 and 18 in such a manner as not to interfere with rotation of the unit.

Attention is directed to the fact that the heat i transfer mediums are introducedinto the rotatable housing 66 througha fiuid'tight gland fit ting that allows rotation of the unit without permitting the escape of the heat transfer-mediums introduced to successively heat and chill the mold transfer mediums flowing inwardly over the outer surfacesof the mold lining members from their peripheries toward the center. As illustrated in Fig. 4 vent forming members 98 may be-positioned in the-core locating ring34 to permit the escape of entrained air and gases formed as molten alloy or metal is introduced into the mold to fillthe oasting cavity. The vent formin members 98 may be of any desired form such for example as sintered powdered metal, porcelain or fibrous material. A illustrated in Fig. 1, the vent members 98'are relatively closely tween the cores and 32 and theinner surfaces of the lower and upper mold'lin'ing members '22 and 24 respectively. A sprue tube 91 is positioned in alignment with'a centrally disposed opening in the upper heat'transfer jacket l8 and-the that the mold lining mem-' upper mold lining member '24 to permit filling the mold. A pouring funnel '95 is positioned on the sprue 91 to-facilitate filling the mold and to increase the hydrostatic pressure on the ca'sting.

The operation is as follows: When the mold'i's" assembled as' illustrated in Figs. 1 to 4, a heat transfer medium such for example as steam, hot

water, hotoilor other suitable heat carrying".

mold lining members 22' and 24 toward the sprue or feeder passages.

will be subjected to a greater degree of heat than the inner portions, and that the heated fluid flows in the direction opposite to the flow of molten alloy ormetal as the casting cavity. is

It will be apparent that the outer edges of the mold lining members 22 and 24 When the mold has been heated to the desired" temperature, the casting headis rotated'to even ly distribute molten alloy or metal in the casting cavity between the cores and the'inner surfaces of the mold lining members by centrifugal diffusion. When the prop'er'speed of rotation has beenattained, molten alloy or metal is introduced through the funnel 95, sprue 91 and spacing tube 3 48,-to fillthe casting cavity. 1

Theiflow of the heated fluid throughthep'as sa'ges '-1lland 82' malntainsthe mold lining members 22 and 24 at sufficiently high temperature to preventsolidification' of thealloy or metal before the'casting cavity is completely filled. Castings having verythin' walled sectionsican thus'be readily cast because themoltenalloy or metal is not subjected to 'sufficient chilling or'cooling ac-- tion tocause it to coagulate or freeze before the casting cavity is completely filled.

As soon asthe casting cavity is completely filled, cooling fluid such for example cold water, oil or other suitable heat transferring medium is circulated'throu'gh the transfer system to absorb heat from the upper and lower mold lining'membe'rs 24 and 22 respectively to'effect rapid solidifi'cationor freezing of the molten alloy or metal to quench the casting and provide a solid casting having a smooth textured surface and fine grained structure. 9

Since the heat transfer mediums flow radially inwardly as the molten alloy or metal is distrib uted'ra'dially outwardlyv in the casting cavity,

the outer edges of the'mold lining members are successively subjected togreater heating and cooling as heated and cooled fluids are successively distributed through the heattransfer pas-'- sage's. When heated fluid is circulatedthrough the heat transfer system, the outer edges of the mold"lining members absorb a greater proportion of heat and asthe outer edges of the mold lining members heat up 'a progressively increasing proportion of the heat is transferred to portions of the mold Iining members spaced radially inwardly. The outer edges of the mold lining members and casting cavity are thus maintained at somewhat higher temperatures than portions spaced radially inwardly toward the feeder or sprue. There is therefore less tendency for the molten alloy or metal to coagulate or solidify as the mold is 'filled until the casting cavity is completely filled. The'formation' of 'very thin cast sectionsis thus insured.

When the'castingcavityhas been filled and cold fiuid :is circulated '"through the transfer system, the outer edges of the mold lining members are first subjected to the cooling effect. As the cooling transfer medium flows" inwardly it is progressively'heated and therefore absorbs progressively less heat as'it flows radially inwardly toward the spr'ue-"o'r' feeder; As heat is progressively transferred from the mold lining members and the "casting being formed more heat will progressively be absorbed from portions of the mold and castingspaced radially inwardly toward the feeder or'sprue; Thesolidification of the molten alloy or metal will therefore start at the outer periphery of the casting and progress inwardly because during the initial stages the coolant absorbs relatively large quantities of heat near thev periphery and therefore cannot absorb asmuch heat, as it flows inwardly. When the periphery has. cooled off .and has solidified,

the proportion. of heat transferred to the coolant from points adjacent theperiphery diminishes,

and moreheat is absorbed from portions of the casting spaced progressivelycloser to the feeder.

It will 'be noted 'that a 'metered quantity of coolant is directed'to the heat transfer space 82 through the passageways l6, l8 and silillustrated in Fig. 3, andthat more-:coolant; is circulated throughthe heat transferspace FIG-around the end of the separator 62. Thelowerportions of the'casting'cavityare therefore subjected to more cooling action than1the upper-portionsand-will therefore :solidifywmorc irapldly;.than :the.=.; upper.

portions.

solidificationprogresses. ,Sin'ce solidification -of the casting progresses ":inwardly'from the peripheryandxfrorn the bottom 'of the casting cavity toward the,gtop,;thegases are driven ahead of the progressive solidification and are forced into the sprue or feeder passage. Solid castings free from. gas inclusions ,andporosity are thus formed. I

The embodiment iof -::the; invention illustrated in Figs. 5 and 6: is similar in many respects to that illustratedrm "Figs. 1. to. 4. Corresponding parts have therefore been given corresponding reference numerals with they addition of-lOO.

The lower moldlining member 122 has. a plurality of radially spaced steps-I I I; I I3 and-I I5 to receive heat imparting means such for example as electrical resistance'elements or strip heaters H1, H9 and I .2I.. The upper mold lining member I24 alsohas a plurality of suitably spaced steps I23, I25 and 121 to receive heating elements129, I3I and"I33.i--A heating element I35 is positioned :around the sprue *I91 to heat the feeder to prevent chilling of the alloy or metal as it is introduced into the casting cavity.

The heating characteristics of the elements associated with spaced portions of the mold lining memberscanbe-varied to permit the application of thewdesired heat intensity to various portions of the mold to insure maintaining the alloy or metal. in the molten condition until the casting cavity is :completely filled. Castings of 7 complex configurations having thin walled sections can thus be readily'cast.

It will be apparent that any type of heating means may be employed, and that if desired the mold lining members I22 and I25 may be of uniform thickness throughout rather than having a plurality of stepped sections. If desired the mold lining members may be of progressively thinner material as the peripheryis approached to insure heating the peripheral portions of the mold to a higher degree than the portions spaced closer to the feeder to maintain a cast molten substance in the fluid state until the casting cavity is completely filled; and to insure progresewe-solidification from-the periphery toward the feeder. V

A spacer --member extends between the lower and. upper coreindex plates M4 and I56. The spacer member has a-lower cylindrical member ISI adapted to project into the lower core index plate I44 and be located with. reference thereto by a fin I63. A radially extended flange I65 carried by the member I BI is provided to overlie the toes or inner ends .I52 .of the cores I 30. The spacer member has vertically extending struts I61 supporting an. upper cylindrical member I59 projecting into the upper core index "plate I56. A fin I1I locates the plate I56 in predetermined angular relation relative tothe lower core index plate I44. 'The upper cylindrical member I69 has a radially extended flange I13 to engage the toes or inner ends of the cores I32.

A pouring spout I extends through the upper mold member I24 to a point adjacent the bottom of the casting cavity. A removable insert I11 formed of non-conducting material may be positioned in the lower cylindrical member IBI beneath the pouringspout I15. The insert I11 has a concave reservoir 115 to -receive molten alloy or metal from thepouring spout I15 to minimize.

" :transfensystemtoremove heat from the molten thermaljishock and distribute the alloy on metal to the casting cavity.

Fig; 'ljlillustrates theqinvention applied .to the static iorgqnon-rotating method, of. casting. -A lowenimold member Z-IG having a mold surface 2 I 2 is provided with a downwardly extending base 2I4 to engage a base or support 2I8. The lower moldmember 2H1 has an upwardly extending flange 218 to receive and support an upper mold member 220 having. amold surface 222.

A:plur ality of removable cores 224 may be interposed between the mold surfaces 2I2 and 222 to cooperate therewith .in the formation. of .a casting cavityof any desired contour or dimensions. The inner andouter ends of the cores 224 may be located and'secured in place in the manner disclosedinthe embodiments of the invention shown in Figs. 1 to 6 or in any manner constituting the mechanical equivalent thereof.

The lower and upper mold members 2H) and 220 may be,-jacketed; to provide heat transfer chambers 226 and228 whereby heated and cooled fluids "may be circulated to heat and cool-the surfaces ;of the mold members and the casting cavity.

A closed circulating system maybe provided to heat or cool the casting cavity forming molds. A pump 230' positioned in a conduit 232 may be provided to withdraw fluid from a heat exchanger orradiator 23 3 having. spaced inlet and outlet passages. The conduit 232 supplies heatedor cooled fluid to branch conduits 236 and 238 communicatin with the chambers 22% and 228 of the lower and upper-m0ld members ZIG and 2-20 respectively. Spaced-outlet conduits 24S and 242 are provided to receive fluid after it has circulated through the chambers 22% and 228 and direct it through a'return conduit 244 to the heat exchanger-or radiator 236.-

When it is desired to heat the mold members preparatory to a casting operation; heated fluid is pumped through the circulating system by the pump 230. Heated fluid may be introduced into an upper-passageway 246 and cooled fluid removed-from a lower passageway 2&8 of the. heat exchanger 234, to impart heat to the medium circulating through the chambers 225 and 228 to heat'the mold members.

A feeder passage 250, preferably centrally disposed with vreference to the casting cavity may extend above the'casting cavity to permit subjecting the casting to hydrostatic pressure. A metering funnel 252 having an outlet 25d centrallydisposed with reference to the feeder passage 250 is secured to the top of the feeder passage byf spaced struts as illustrated. The metering funnel "252 has a perforated disk 25% to act as a strainer to prevent impurities in the molten alloy or metal from being introduced into the casting cavity.

The perforated disk 256 or the outlet 254 of the metering funnel 252 function to control the rate 'offilling of the casting cavity, and insure introducing the molten alloy or metal through the centerof thefeeder passage 25d. Entrained air and gases can thus readily escape fromthe casting cavity between the inflowing alloy or metal and the walls of the feeder passage 250.

I Whenthe desired mold temperature has been attained, molten. alloy or metal may be introduced intopthe casting cavity through a sprue 25H. When the'casting cavity is filled, chilled or cold fluid may be circulated through theheat 9 material introduced into the casting cavity to effect rapid solidification of the casting.

If desired the pump 236 may be connected to another heat exchanger controlled by suitable valving mechanism to interrupt the flow of heated fluid from the heat exchanger 234 and direct cooled or cold fluid from the other heat exchanger through the conduit 232 and chambers 226 and 228 to effect rapid solidification of the casting.

In instances where the heat exchanger 234 is used to both heat and cool the fluid, cooled fluid is preferably introduced into the heat exchanger through thelower passageway 248 and heated fluid is withdrawn from the upper passageway 246.

It will be apparent that if desired the heated or cooled fluids may be introduced into the chambers 226 and 228 of the mold members adjacent their peripheries and be discharged adjacent the center or sprue as disclosed in the embodiment illustrated in Figs. 1 to 4 if the desired progressive heating and cooling of the mold to insure complete filling of the casting cavity and to efiect progressive solidification of the casting is not attained. Also it will be apparent that the passages 236 and 238 may if desired be of somewhat different sizes to permit controllin the heating and cooling of the lower and upper sections of the mold. For example a greater quantity of fluid may be introduced into the chamber 226 to apply greater heat or cold to the'lower portion of the casting cavity to insure complete fillingof the casting cavity and progressive solidification of the casting toward the feeder.

It will be understood that in the formation of large castings, fluid circulating passages may extend into the castingcavity to insure obtaining the desired heat transfer characteristics. For example certain or all of the core members employed to cooperate with the mold members to shape the desired casting cavity may be hollowed out to permit the flow of heating or cooling fluid therethrough. Where this expedient is resorted to, the core members may have hollow sections formed of metal or plastic material to direct the flow of heating or cooling fluid and to prevent disintegration of the care when the heating or cooling fluid passes through it. The core forming material such as plaster or other suitable substance having for example a silica base where castings of high temperature alloy or metals are to be formed bonds to the surface of the hollow liners employed to provide the heat transfer passageways. The fluid flow through the core may be from the periphery inwardly toward the center or feeder passage to insure the desired progressive heating and cooling.

It will be understood that features disclosed in connection with one embodiment of this invention can be used with any of the other embodiments disclosed herein.

I claim:

1. In a mold structure, an inner housing having an opening, an indexing ring adjacent the opening, an indexing ring adjacent the periphery of the housing, a series of core elements supported on the indexing rings within the housing, a sprue having parts embracing the indexing ring adjacent the opening and another part bearing against the core elements, and a feeding tube extended through the opening and positioned to discharge into the sprue.

2. In a mold structure, an inner housing having an opening, an indexing ring adjacent the opening, an indexingring adjacent the periphery of the housing, a series of core elements supported on the indexing rings within the housing, a sprue having parts embracing the indexing ring adjacent the opening and another part bearing against the core elements, and a feeding tube extending through the opening and seated on the indexing ring adjacent the opening.

RAYMOND J. MILLER.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 2,253,771 Dulaney Aug. 26, 1941 2,369,067 Mayer Feb. 6, 1945 2,429,146 Wessel Oct. 14, 1947 FOREIGN PATENTS Number Country Date 877,104 France Aug. 24, 1942 

